FLORA OF WASHINGTON AND VICINITY. 117 



Po23ulus balsamifera, L., var. candicars, Gray. Balm op Gilead. 

 Last half of April. 



Populus diJatata, Ait. Lombardy Poplar. 

 Potomac City, along the Eastern Branch. 



Populus alba, L. Abele. White Poplar. 



Tending to spread and form groves. There are two forms in the city, one of which 

 has small leaves which are scarcely at all whitened underneath. These are all male 

 trees. February or March. 



CERATOPHYLLACE^. 



HoRNWORT Family. 



Ceratophyllum demersum, L. Hornwort. 

 Abundant in the Potomac. July. 



. MONOCOTYLEDONS. 



ARACEiE. 



Arum Family. 



t Arisaema triphyllum, Torr. Indian Turnip. 



April; fruit, July. 



tArisasma Dracontium, Schott. Green Dragon-root. 

 High Island ; Carroll Estate. May; fruit, August. 



tPeltandra Virginica, Raf. Arrow Arum. 

 Leaves sometimes reduced to a simple elliptical blade. July. 



t Symplocarpus foetidus, Salisb. Skunk Cabbage. 

 February, March. 



tOrontium aquaticum, L. Golden Club. 

 May, June. 



t Acorus Calamus, L. Sweet Flag. Calamus. 



June. 



LEMNACE-ai. 



Duck-weed Family. 



Lemua polyrrhiza, L. Duckweed. Duck's-meat. 



TYPHACEiE. 



Cat-tail Family. 



1 Typha latifolia, L. Common Cat- tail. Reed-mace. 

 June. 



t Typha angustifolia, L. Small Cat-tail. Narrow-leaved Cat-tail. 

 Last week in May. 



t Sparganium eurycarpum, Eng. Bur-reed. 

 Julv. 



